1. Field
Aspects of embodiments of the present invention relate to a mask for laser induced thermal imaging and a method of fabricating an organic electro-luminescence display device, and more particularly, to a mask for laser induced thermal imaging capable of preventing or substantially preventing damage of a laser generator due to a laser beam reflected by the mask.
2. Description of the Related Art
Generally, as a flat display device, an organic electro-luminescence device includes an anode electrode, a cathode electrode, and organic layers interposed between the anode electrode and the cathode electrode. The organic layers at least include an emission layer and may further include a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), and an electron injection layer (EIL) besides the emission layer. The organic electro-luminescence device may be classified as a high molecular organic electro-luminescence device or a low molecular organic electro-luminescence device according to a material forming the organic layer, in particular, the emission layer.
In the organic electro-luminescence device, in order to implement a full color, the emission layer should be patterned. As a method for patterning the emission layer, there is a method of using a shadow mask in the case of the low molecular organic electro-luminescence device and a method of ink-jet printing or laser induced thermal imaging (hereinafter, referred to as LITI) in the case of the high molecular organic electro-luminescence device. Among these, there are advantages in that the LITI can finely pattern the organic layer, be used in a large area, and achieve high resolution. Further, the ink-jet printing uses a wet process, while there is an advantage in that the LITI uses a dry process.
FIG. 1 is a schematic cross-sectional view for illustrating a method for forming a pattern of an organic layer using LITI.
Referring to FIG. 1, a donor substrate 120 on which an organic layer 130 is formed is laminated on a substrate 110 on which predetermined devices are formed. If a laser beam 150 is irradiated in a predetermined region of the donor substrate 120 on which the organic layer 130 is formed, the laser beam is absorbed into a photo-thermal converting layer of the donor substrate 120, which is in turn converted into thermal energy. Meanwhile, the organic layer 130 forming a transfer layer by the thermal energy is transferred onto the substrate 110, thereby forming the organic layer pattern. In this case, the organic layer 130 is separated from the donor substrate 120 due to the thermal energy and is transferred onto the substrate 110 while the coupling in the organic layer 130 is broken. Energy necessary to break the coupling in the organic layer 130 should be larger than energy necessary to separate and transfer the organic layer 130 from the donor substrate 120. A dotted line portion shows a portion where the coupling in the organic layer 130 is broken.
FIG. 2A is a schematic diagram for illustrating a method for fabricating an organic electro-luminescence device using a laser irradiating apparatus according to the related art.
Referring to FIG. 2A, the donor substrate 120 on which the organic layer 130 is formed is laminated on the substrate 110 on which predetermined devices are formed. The laser irradiating apparatus 200 includes a laser generator 240, a patterned mask 260, and a projection lens 270. The laser generator 240 irradiates a laser beam 250 into the predetermined region of the donor substrate 120. In this case, the laser beam 250 irradiated from the laser generator 240 passes through the patterned mask 260, and the laser beam 250 passing through the patterned mask 260 is refracted by the projection lens 270 and is irradiated onto the donor substrate 120. The laser beam 250 is shielded in an unpatterned portion of the mask 260.
The organic layer 130 on the donor substrate 120 is transferred onto the substrate 110 by the laser beam 250. After the transfer process, the cathode electrode is formed on the formed organic layer pattern, thereby completing the organic electro-luminescence device.
FIG. 2B is a schematic cross-sectional view for illustrating a problem of the laser irradiating apparatus according to the related art. Referring to FIG. 2B, the laser irradiating apparatus according to the related art passes the laser beam 250a to a patterned portion 260a of the mask 260 and transfers the organic layer 130 on the donor substrate 120 to the substrate 110 by the laser beam 250a, as described above. The laser beam 250b is reflected in an unpatterned portion 260b of the mask, i.e., in a portion where the laser beam 250 is shielded by the mask 260, and, as a result, may damage the laser generator 240.
That is, the above-mentioned mask is made of a metallic material to completely shield the laser beam 250b at the unpatterned portion 260b of the mask 260 and irradiate the laser beam 250a only at the patterned portion 260a, thereby making it possible to accurately irradiate the laser beam 250 to the donor substrate 120. However, the above-described mask 260 has a problem of damaging the laser generator 240 due to the laser beam 250b being reflected by the unpatterned portion 260b of the mask 260.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.